Chris M schrieb:
> Andreas Michalowski wrote:
>> Ok, I will report the bug to the sourceforge site as soon as I
>> recover my password. ;)
>> The question is how meaningful the bugfix for the depreciated
>> "convolve" and "fftconvolve" is. My suggestion is to realize the idea
>> of sisyphus: The replacement of convolve and fftconvolve with
>> convolveND, namely inside the PDL sources if possible. What do you
>> think?
>
> I checked my PDL-2.4.3 install and the docs for convolve
> say deprecated, use convolveND. So moving to a convolveND
> implementation would seem reasonable. Please do submit
> your bug report to the PDL sf.net tracker so that this will
> get to the to-do list.
>
> We do not have a new version of fftconvolve so that
> would not be replaced---the FFT convolution algorithm
> has much better performance for the case of very large
> kernels.
>
> Regards,
> Chris
I thought convolveND has also FFT properties, because the documentation
of convolveND says:
-----------
*method (default: 'auto')*
The method to use for the convolution. Acceptable alternatives are
'direct', 'fft', or 'auto'. The direct method is an explicit
copy-and-multiply operation; the fft method takes the Fourier
transform of the input and output kernels. The two methods give the
same answer to within double-precision numerical roundoff. The fft
method is much faster for large kernels; the direct method is faster
for tiny kernels. The tradeoff occurs when the array has about 400x
more pixels than the kernel.
The default method is 'auto', which chooses direct or fft
convolution based on the size of the input arrays.
-----------
Is this a wrong information? (I'am PDL novice)
regards,
Andreas
--
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Dipl. - Phys. Andreas Michalowski
Institut für Strahlwerkzeuge (IFSW)
Universität Stuttgart
Pfaffenwaldring 43
D-70569 Stuttgart, Germany
Phone ++49-(0)711-6856-9735
Fax ++49-(0)711-6856-7244
e-mail: [email protected]
http://www.ifsw.uni-stuttgart.de
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